Ruby introduction for newbies

Ruby introduction for newbies. A presentation me & Sidu did at Bangalore Ruby user group meeting

1. RUBY Hemant & Sidu Saturday 16 June 12
2. RUBY LANGUAGE Ruby is a object oriented programming language deeply inspired by Smalltalk, Lisp & Perl. It is also a dynamic but strongly typed language. Saturday 16 June 12
3. ABOUT DYNAMIC LANGUAGES Dynamically Typed. Dynamic Language. Saturday 16 June 12
4. STRONGLY TYPED Javascript 1 + "Hello" => "1Hello" Ruby 1 + "Hello" => TypeError class Fixnum def +(other); "#{self}#{other}"; end end Saturday 16 June 12
5. Javascript collect_milk([cow, hen,python]) Ruby collect_milk([cow, hen,python]) Saturday 16 June 12
6. CLASSES & OBJECTS Everything in Ruby is a object methods classes lambdas integers Saturday 16 June 12
7. CLASSES class Car def initialize @name = "Ferrari" end def say_name puts @name end end ferrari = Car.new() ferrari.say_name Saturday 16 June 12
8. CLASSES class Car def initialize @name = "Ferrari" end def say_name puts @name end end ferrari = Car.new() ferrari.say_name Output: Ferrari Saturday 16 June 12
9. MODULES A Module is a collection of methods and constants. Instance methods appear as methods in a class when the module is included. Saturday 16 June 12
10. MODULES module AnimalBehaviour def eat puts "Eating now" end end class Dog include AnimalBehaviour end tommy = Dog.new() tommy.eat() Saturday 16 June 12
11. MODULES module AnimalBehaviour def eat puts "Eating now" end end class Dog include AnimalBehaviour end tommy = Dog.new() tommy.eat() Output : Eating now Saturday 16 June 12
12. CLASS HIERARCHY Saturday 16 June 12
13. Saturday 16 June 12
14. class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
15. Car class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
16. Car Object class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
17. Car Object class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
18. Car Object BasicObject class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
19. Car Object BasicObject class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
20. Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
21. Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
22. Class Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
23. Class Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
24. Class Module Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
25. Class Module Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
26. Class Module Object Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
27. Class Module Object Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
28. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
29. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
30. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
31. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
32. Class Module Object BasicObject Car Object BasicObject ferrari = Car.new class Car def initialize @name = "Ferrari" end end Saturday 16 June 12
33. RECAP Saturday 16 June 12
34. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Saturday 16 June 12
35. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Saturday 16 June 12
36. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Saturday 16 June 12
37. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object Saturday 16 June 12
38. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12
39. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12
40. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12
41. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12
42. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12
43. RECAP module AnimalBehaviour def eat puts "Eating now" end end class Dog end tommy = Dog.new() tommy.eat() Class Module Object BasicObject Saturday 16 June 12
44. OBJECT VS BASICOBJECT class Object < BasicObject include Kernel end Saturday 16 June 12
45. VARIABLES module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12
46. module GameWorld class Planet def initialize(name) @name = name end def name @name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12
47. module GameWorld class Planet def initialize(name) @name = name end def name @name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() earth = Planet.new("Earth") earth.name Saturday 16 June 12
48. module GameWorld class Planet def initialize(name) @name = name end def name @name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def position @position end end end alien = GameWorld::Alien.make_alien() earth = Planet.new("Earth") earth.name Output : Earth Saturday 16 June 12
49. module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.alien_count @alien_count end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12
50. module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.alien_count @alien_count end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.alien_count Saturday 16 June 12
51. module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.alien_count @alien_count end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.alien_count Output : 1 Saturday 16 June 12
52. module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.planet @@planet end def position @position end end end alien = GameWorld::Alien.make_alien() Saturday 16 June 12
53. module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.planet @@planet end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.planet Saturday 16 June 12
54. module GameWorld class Planet def initialize(name) @name = name end end class Alien @alien_count = 0 @@planet = Planet.new("Mars") def self.make_alien @alien_count += 1 alien end def self.planet @@planet end def position @position end end end alien = GameWorld::Alien.make_alien() Alien.planet Output : Planet(“Mars”) Saturday 16 June 12
55. http://www.ruby-doc.org/core-1.9.3/BasicObject.html Ruby 1.8 does not have BasicObject Metaclass Saturday 16 June 12
56. DUCK TYPING Saturday 16 June 12
57. DUCK TYPING class Cow def milkit; end end class Goat def milkit; end end Saturday 16 June 12
58. DUCK TYPING def collect_milk(animal) if animal.respond_to?(:milkit) animal.milkit else raise InvalidArgument.new("Cant milk #{animal.inspect}") end end class Cow def milkit; end end class Goat def milkit; end end Saturday 16 June 12
59. Embrace Duck typing Saturday 16 June 12
60. def collect_milk(animal) if animal.is_a?(Cow) animal.milkit end end Saturday 16 June 12
61. Saturday 16 June 12
62. def collect_milk(animal) if animal.respond_to?(:milkit) animal.milkit else raise InvalidArgument.new("Cant milk #{animal.inspect}") end end Saturday 16 June 12
63. EMBRACE POLYMORPHISM Saturday 16 June 12
64. def total_score(test) if test.is_a?(EnglishTest) test.subjective_score elsif test.is_a?(MathTest) test.total_marks end end Saturday 16 June 12
65. class EnglishTest def total_score end end class MathTest def total_score end end test.total_score Saturday 16 June 12
66. NAH I AM NOT THAT DUMB Saturday 16 June 12
67. HASH student_scores = { hemant: {math: 10, science: 20, total: 30}, kiran: {math: 20, science: 30, total: 50}, sidu: {math: 20, science: 30, total: 50} } Saturday 16 June 12
68. USE BUT DON’T ABUSE HASH Saturday 16 June 12
69. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Saturday 16 June 12
70. Saturday 16 June 12
71. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Saturday 16 June 12
72. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Saturday 16 June 12
73. def scrap_pirate_bay(response) scrap_output = {} scrap_output[:title] = response.title ? response.title : "Pirates Rule" scrap_output[:body] = response.body scrap_output end Use a Class Saturday 16 June 12
74. OMFG performance and garbage collector What is wrong with hashes? Saturday 16 June 12
75. You Mad Bro? Saturday 16 June 12
76. KNOW THY DATA STRUCTURES fruits = ["apple","orange","apple"] fruits.uniq fruits = Set.new() fruits += ["apple","orange","apple"] Saturday 16 June 12
77. KNOW THY DATA STRUCTURES fruits = ["apple","orange","apple"] fruits.uniq fruits = Set.new() fruits += ["apple","orange","apple"] Output : [“apple”,”orange”] Saturday 16 June 12
78. DEFINE YOUR CLASSES INSIDE MODULES Saturday 16 June 12
79. module Leman class Ferrari end class Maruti800 end end Saturday 16 June 12
80. IMO in Rails - DHH did a mistake by putting all the module, controller, helpers in global scope Saturday 16 June 12
81. Saturday 16 June 12
82. Saturday 16 June 12
83. LAMBDAS Saturday 16 June 12
84. I DON’T KNOW WHY THEY EVEN EXISTS! Saturday 16 June 12
85. Saturday 16 June 12
86. I know why it exists and I am using them with ActiveRecord scopes. But can never think why will my own method need a lambda. Saturday 16 June 12
87. fortune_cookie = lambda { stocks = ['GROUPON','FACEBOOK','ZYNGA'] puts "You should invest in #{stocks[rand(3)]}" end fortune_cookie.call() Saturday 16 June 12
88. fortune_cookie = lambda { stocks = ['GROUPON','FACEBOOK','ZYNGA'] puts "You should invest in #{stocks[rand(3)]}" end fortune_cookie.call() You should invest in GROUPON Saturday 16 June 12
89. YOU CAN PASS THEM AS ARGUMENTS class MailParser def parse(filename,mailer) mail_object = do_some_hocus_pocus(filename) mailer.call(mail_object) ensure filename.close() end end mail_parser = MailParser.new() mail_parser.parse("foo.mail", lambda { |mail| mail.send() }) Saturday 16 June 12
90. AS ANONYMOUS FUNCTION Saturday 16 June 12
91. AS ANONYMOUS FUNCTION def shoot(target,gun, crouch_flag = false) return true if target.dead? loop { if gun.has_bullets? dead_yet = target.shoot(gun,crouch_flag) if dead_yet break end else gun.reload end } end Saturday 16 June 12
92. AS ANONYMOUS FUNCTION def shoot(target,gun, crouch_flag = false) shoot_algo = lambda do return false if gun.has_bullets? target.shoot(gun,crouch_flag) end return true if target.dead? loop { x = shoot_algo.call() x ? break : gun.reload } end def shoot(target,gun, crouch_flag = false) return true if target.dead? loop { if gun.has_bullets? dead_yet = target.shoot(gun,crouch_flag) if dead_yet break end else gun.reload end } end Saturday 16 June 12
93. BLOCKS & LAMBDAS Saturday 16 June 12
94. BROTHERS IN ARMS Saturday 16 June 12
95. class MailParser def parse(filename) mail_object = do_some_hocus_pocus(filename) yield mail_object ensure filename.close() end end mail_parser = MailParser.new() mail_parser.parse("foo.mail") {|mail| mail.send } Saturday 16 June 12
96. class MailParser def parse(filename) mail_object = do_some_hocus_pocus(filename) yield mail_object ensure filename.close() end end mail_parser = MailParser.new() mail_parser.parse("foo.mail") {|mail| mail.send } Saturday 16 June 12
97. http://eli.thegreenplace.net/2006/04/18/understanding-ruby- blocks-procs-and-methods/ Saturday 16 June 12
98. EAT THEM FOR BREAKFAST & LUNCH Saturday 16 June 12
99. META- PROGRAMMING Saturday 16 June 12
100. Saturday 16 June 12
101. 0 22.5 45 67.5 90 Newbie Can hold my ground Expert Guru Meta Programming Usage Saturday 16 June 12
102. 0 22.5 45 67.5 90 Newbie Can hold my ground Expert Guru Meta Programming Usage You know nothing John Snow Saturday 16 June 12
103. 0 22.5 45 67.5 90 No Understand Kinda Understand Public Enemy Guru Meta Programming Usage Saturday 16 June 12
104. 0 22.5 45 67.5 90 No Understand Kinda Understand Public Enemy Guru Meta Programming Usage You know nothing John Snow Saturday 16 June 12
105. http://pragprog.com/screencasts/v-dtrubyom/the-ruby-object- model-and-metaprogramming Saturday 16 June 12
106. ENGINEERING IS NOT OPTIONAL Saturday 16 June 12
107. DESIGN IS NOT JUST FOR DESIGNERS Saturday 16 June 12
108. OO IS NOT JUST FOR JAVA PROJECTS Saturday 16 June 12
109. SE IS ABOUT PEOPLE Saturday 16 June 12
110. STUDY PEOPLE STUDY PRODUCTIVITY Saturday 16 June 12